jacobus



- Sept. 24, 1929.. p. s. JACOBUS 1,729,259

STEAM BOILER ECONOMIZER Original Filed Sept. 4. 191.8

9 Sheets-Sheet l BY gww M TTORNEYS.

Sept. 24, 1929. D: s. .uacosus l,72,259

STEAM BOILER ECONOMI ZER Original Filed Sept. 4. 1918 9 Sheets-Sheet 2 Sept. 24, 1929. D. s. JACOBUS- 1,729,259

sTEAu BOILER ECONOMIZER firiginal' Filed Sept. 4. 1918 9 sheets-sheet a- IN VEN TOR. BY ig w //1/. ATTORNEYS;

Sept. 24,

I D. S. JACOBUS STEAM BOILER ECONOMIZER Original Filed Sept. 4, 1918 v9 Sheets-Sheet INVENTOR.

,/A4' ATTORNEYS.

Sept. 24, 1929.- D, ACOB S 1,729,259

STEAM BOILER ECONOMIZER Original Filed Sept. 4, 1918 9 Sheets-Sheet 5 i J I I VENTOR.

:H' A) S /h ATTORNEYS.

Sept. 24, 1929. s 0

STEAM BOILER ECONOMIZER Original Filed Sept. 4. 1918 9 Sheets-Sheet 6 mm H w fill ilwrn! IL .36 uS \KQQ h lit 7 Z k l 1 INVENTOR. AMS. 4

BY I 4 ATTORNEYS.

P 2 D. s. JAco us 1,729,259

STEAM B OILLER ECONQMIZER Original Filed Sept. 4. 1918 9 Sheets-Sheet =7 ui g;

NVENTOR.

Sept. 24; 1929. D. s. JACOBUS 9 STEAM BOILER ECONOMI ZER Original Filed Sept. 4. 1918 9 Sheets-Sheet 8 ,8 INVENTOR.

BY M

//M' ATTORNEYS.

Sept. 24, 1929.

D. s. JACOBUS 1,729,259

STEAM BOILER ECONOMI ZER Original Filed Sept. 4. 1918 9 Sheets-Sheet 9 N VEN TOR.

Patented Sept. 24,1929

UNITED STATES PATENT OFFICE.

DAVID S. J'ACOIBUStOF JERSEY CITY, NEW JEREY, ASSIGNOR TO'THE BABOOCK & WILGOX COMPANY, OF BAYONNE, NEW JERSEY, A CORPORATION OF NEW JERSEY STEAM-BOILER ECONOMIZER Applicationfiled September 4, 1918, Serial No. asasso. Renewed December 13, 1927.

Figure 1 is a sectional sideelevation, showing one form or my improved system and taken on the line I,I of Fig. 2; Fig. 2 1s a top plan view, of Fig. 1 partly broken away;

Fig. 3 is a detail vi W of the special cross boxes and connectio Fig. 4 is a View taken on the lines.IV-IV of Figs. 1 and 2; Fig. 5

is a sectional side elevation showing a modified form and setting of the economizer; Fig.

6 is a front elevation, partly in section, showing the form of Fig. 5; Fig. 7 is a sectional view of the header boxes of the special economizer, showingthe method of removing and replacing the tubes; Fig. 8 illustrates the laspacing of the superheater tubes of Fig. 5; Fig. 9 shows the spacing of the boiler tubes of Fig. 6; Fig. 10 is an enlarged section of the special economizer box and tubes on the line XX of Fig. 11; Fig. 11 is a cross section on the line XIXI of Fig. 1 Fig. 12 is a View similar to Fig. 10, taken on the line XII-XII of Fig. 13 and showing circular headers with eight rows of tubes; Fig. 13 is a cross section on the line XIIIXIII of Fig.

12; Fig. 14 isa view similar to 1'0, takenon theline XIVXIV of Fig. 15 and showing a special form of header box with eight rows of tubes; Fig. 15 is a crosssection on the line XVXV of-Fig. 14; F ig. 16 is a view similar to Fig. 14, taken on the line XVI XVI of Fig. 17 and showing six-rows of tubes; Fig. 17 is a cross section on theline XVII-XVII of Fig. 16; Fig. 18 is a cross section showing squared forms of headers set in pairs with spaces between the pairs for removal and insertion-10f tubes; andFig. 19 is a cross section through the separate portions of the tubes of Fig. 18.

My invention'relates to devices for heating fluids, particularly such as are known as ;econo1nizers used in connection with steam boilers to heat the feed water, and consists in certain arrangements of such devices by which they maybe more economically constructed an more efficiently operated, together with certain other features hereinafter more specifically set forth in the appended claims.

Referring to the form ofFigs. 1, 2, 3 and 4, 1 and 2 represent the steam and water drums of a pair of boilers in the upper horizontally extending outlet flues of which are placed economizers numbered generally 3 and v 4. .The gases flow through the economizer 3 in the opposite direction to that through which they flow in the economizer 4, as shown in the patent to Sargent and myself, granted December 31, 1912, N0. 1,048,7 39.

' As shown in these figures, each economizer is made up of six banks of tubes numbered 5 to 10, inclusive, the gases from the boiler first coming in contact with the bank of tubes 5 and finally in contact with the last bank of tubes 10, and passing to a fan 11, by which e they are discharged into the uptake 12.

As shown in the broken away portion of Fig. 2, the header boxes or. manifolds extend longitudinally of the flow of the gases and these boxes in each group are spaced apart to allowthe dust and soot to drop down between the headers and collect in hoppers 28, having access doors 29. The hoppers 28.are preferably symmetrically arranged with respect to e the banks of tubes of theeconomizer, as indicated in Fig. 1, the edges of the hoppers" being sealed against the economizer headers, as in- 7 dicated in general at 47, the seals preferably comprising cross members 48, here shown as channel-irons, which serve also as supports for the ends of the sections of the header boxes.

Steam or compressed air dusting devices are shown at 13 and 14, these comprising rotating jet pipes having jet outlets arranged in proper locations to blow off the soot and dust from the tubes, these being preferably located near the ends of the tubes, as shown.

The feedwater for the economizer 3 enters the cross box 16 through the pipe 15 and from this cross box it is fed through a series of nipples into the headers 17 of the bank. 10.

It flows upwardly in parallel through the tubesof the bank 10 to the corresponding longitudinal upper headers 18, whence it flows to the upper cross box 19 and thence down through the tube 20 to the lower cross box 21 and headers 22 of the bank 9. The water then flows up through the tubes of the bank 9 to the upper headers 23, thence into the cross box 24, thence downwardly through the pipe 25, continuing from section to section of economizer until it reaches the upper cross hex 2? of the section 5 whence it passes through the pipe 2h to the boiler 1.

Fig. 3 illustrates the connections of one of the cross boxes, such as 19 and the header boxes 18 with the nippie connections.

The sootmay be removed from the headers by a draft suction system connected to the pipe 30,, sliding dampers 31 being employed the hopper connections. 1

As shown in cross section of Figure 4-. wherein the gases flow at right angles to the plane of the paper, the soot falling from the economizer tubes will readily pass down- Wards in the spaces between the headers. The soot dusters 13 and 1-2 are preferably rotated to project the jets at difierent angles so as to reach all parts of the tubes. is shown in Figures 3 and 4, the end portions of some of these tuhes are bent so as to 1 rovide substantially uniform spacing o the tubes through the greater part of the cross section of the flue through which the ases flow. This gives a good distribution 0 heat over the economizer surface and efiicient absorph'on.

In Figures 5 to 9, inclusive, I show a modified form of economizer wherein the high pressure stage formed in accordance with my invention is set broadside at the front of the boiler, and the gases a ain flow longitudi- MB of the headers, but in cross passes through the tubes of the high pressure stage before passing to another section of the economizer, preferably at low pressure.

The gases from the boiler 33 pass longitudinally of the lower economizer headers and across the tubes, being directed by cross baffling projecting in from the opposite sides and leave the upper part of the economizer also longitudinally of the upper headers and enter and pass through an economizer 35 which may be of any desired type. It is shown as a cast iron construction having scraping devices for removing soot or deposit from the tubes. From the economizer 35 the gases pass to the fan 36 and thence upward through the outlet connection '37. In the form herein shown, the economizer 35 forms the low pressure stage and the economizer 32 the high pressure stage, the

water first passing through the low pressure stage an-lthcucc through the pipe 39 to a tank 40, ark-ere the air and gases are allowed to escape.

The water from the low ressure economizer drops down over a ser1es of shelves in pressure economizer 32. Water from the hot well, or other source of heated Water may be fed into the economizer 35 through the pipe 38, and thence into the tank 40 through the pipe 39. The proper level in the tank as may be maintained by a float which regulates a valve in .the pipe 38 as shown. The'air and. gases released from the tank pass oii' through apipe which may lead direct to the armies phere or to a vacuum pum Live steam may also be fed into the tank, idesired.

The general arrangement of the tank etc, may he that set forth in my cry-pending application Serial No. 124,513, filed lctoher 9, 1916., for economizer boilers.

The form of the high pressure economizer and the employment oi the relatirel long tubes makes it especially adaptahie tor the high pressure element in a two-stage economizer to raise the temperature of the water entering the boiler up to nearly or actually up to the steaming point of the water in the boiler, as the high pressure element 32 will not tend to belch over as great an amount of water into the boiler as would be hclchcd over with many other forms of economizer-s should steaming occur in the economizer. The comparative absence of troilble through belching over water with the form of high pressure economizer herein described arises through the freedom with which the steam can ascend through the vertical tubes into the cross header 32 which extends from side to side of the economizer. The local circulation set up in the economizer also assists in preventing a quick steaming action when the operating conditions are irregular.

The particular arrangement of boiler and two-stage economizer shown in Figure 5 is of special advantage in reducing the amount of. 1

floor space required for the combined hoiler and economizer. The high pressure clement ofthe economizer is placed in what would normally be used as a flue for conducting the gases to an economizer above the boiler, thus minimizing the floor space. The volume of the entire setting is also reduced to a minimum, thus reducing radiation losses and losses through leakage of air into the setting.

The general arrangement of the header boxes and tubes in the economizer 32 is similar to that of the economizer 3 in Figure 1, as more clearly shown in Figure 6, which shows the tubes equally spaced for the greater part of their length with the ends of certain tubes bent to enter the header boxes, as shorgn in Figure 7. As shown in this figure, every other tube is bent outwardly to give substantially equal spacing for fi=- greater part of the tube length. In rem vi7.g Rd replacing the tubes in the economizer'they are taken outhole in the opposite box, and is then drawn to jacent rows.

its proper position with respect to each of the boxes and the ends of the tube expanded to make a tight joint. It will be noted that with the arrangement shown, an entire section formed of the two header boxes and the nest of tubes col'inecting them, may be removed and replaced by bodily movement of the section with respect to adjacent sections. Individual tubes may also be removed and at the same time, the spacing of tubes across the device is substantially uniform. The handholes provided in the header boxes afford ready access to the interior of the header boxes at the ends of the tubes, for installation and repair, or cleaning thereof.

As shown in Figure 8, the tubes of the superheater 44 shown in Figure ,5, are preferably spaced directly over each other; while the boiler tubes as shown in partial section of Fig-' ure 9, are preferably staggered in the usual manner.

In Figures 10 and 11, I show, on an enlarged scale, the'method of bending the ends of the tubes and attaching them to the economizer headers. The tube shown in dotted lines between the headers illustrate the manner of removing and replacing tubes. The direction of the flow of gases isat right angles to the plane of the drawing in Fig ure 10 and parallel with the header boxes in Figure 11. As shown, in Figure 11, the straight portions of the tubes present a staggered arrangement to the flow of the gases, this staggering varying slightly in order to secure easy construction and allow bending of the ends of only one-half of the tubes. [11 the form illustrated, the boxes are provided with rows of holes equally spaced and in each row there is inserted alternately a straight and a bent tube, the ,bent tubes of each outer row extending out over the spaces between the lower header boxes. By making the adjacent sections or groups alike, the

bent tube of one section falls opposite the space between two bent tubes of the outerrow of the adjacent section, which results in a substantially uniform spacing of thetubes .in the gas outlet, with the tubes of each row staggered in relation to the tubes of the ad- Thus the advantage of a good distribution of the tubes for eflicient heat absorption is obtained, while at the same time, the headers can be drilled with uniformly spaced holes for the tubes. The headers are spaced apart to permit the dust to drop and the minimumnumber of tubes are bent.

The spacing of the header boxes is such .tinuous.

that the individual nests of tubes may be removed between alternate boxes and for this purpose, it is desirable that the spacing between alternate boxes, shall be at least as great as the width of the tube nest in the section between such boxes. In other words. considering three consecutive boxes, the clear distance between the wall of the first box and the adjacent wall of the third box should be at least as great as the overall width of the tubes in the nest connected to the second box and disposed between the first and third boxes. By this arrangement, it will be seen that the entire nest may be removed bodily.

Figure 12 shows a similar arrangement of header boxes, but the header. boxes 45 are cylindrical and eight rows of tubes are shown, the manner of replacing betweenthe header boxes being also shown. In this case again soot and dust drop in the spaces between the headers in boxes placed beneath. In most cases the tubes would be removed by passing them between the uppermost headers ofthe economizer, which are preferably of the same size and spaced the same as the lowermost headers.

As shown in Figure 13 the tubes are arranged in pairs of transversely extending rows, the tubes of each row being staggered with respect to those in the other row of the pair, with a wider space between each pair of rows of tubes for the removal of tubes than exists between the rows of tubes in a pair.

Figures 14 and 15 show a form similar to Figures 12 and 13, but with headers 46 of a special shape to render easier the inserting and expanding of the tube ends. Each header or manifold is here shown as comprisinga portion of generally circular crosssection with a portion of much larger radius forming the part of. the manifold to which the tubes are connected. By this arrangement, the tubes may be expanded into this portion of relatively large radius, which they may enter substantially perpendicular thereto. At the same time, the curves which form the perimeter of the section are con- Here again the tubes are "in staggered relation to the direction of flow and sufiicient space is left between the rows of'tubes for the removal and replacement of tubes instead of allowing a space between every two rows of tubes, as shown in Figure 13. Figures 16 and 17 show a form similar to that of Figures 14 and 15,,but with six rows of tubes instead of eight rows.

Figures 18 and 19 show a form wherein the'header boxes are set together in pairs with spaces between the successive pairs for removing and replacing the economizer tubes. Itwill be noted that the tubes are so set that in removing and replacing they can be passed between each two lines of tubes in the same way as in Figures 13 and 17.

As the tubes are introduced by passing them first into one box and then backing them up into the opposite box, the handhole tubes. In the various forms shown in Figs. 10

to 19 inclusive, I have shown various dimensions to indicate the spacing of tubes, and of boxes. These dimensions are of course merely exemplary and are not limiting. They merely show possible dimensions which may be adopted for the various constructions' shown.

The advantages of my invention result from the arranging of the economizer header boxes to provide for dropping down of soot and dirt. between them and also allowing for easy removal and replacement of tubes. It also results from the staggering of the tubes by bending the ends of part of them and from the provision for easy insertion of steam or air dusters for blowing off the soot, etc.

Again, a local circulation may take place in each bank of tubes of the economizer, the

'water passing down some of the tubes and up other of the tubes. This local circulation is promoted by the arrangement of the header boxes longitudinally of the flow of the gases, as it will be apparent that such a circulation is brought about by the longitudinal arrangement of the boxes, and will be much greater than would be the case where the boxes are arranged transversely of the flow of the gases, and in which it will be apparent that any local circulation will be greatly restricted or' entirely prevented. This local circulation will be highly beneficial in the form of Figure 5, for should the feed be irregular, the local circulation during the time-when there is a lack of feed water would cause the hot gases to act on all the water in the economizer and the active flow of water or steam through the parts of the economizer surface would prevent local-overheating. It can readily be appreciated. that with a restricted circulation, with the feed water shut oil", the tubes which come nearest the boiler and are contacted witlrby the hottest gases will become hotter than the tubes which are farthest removed from the boiler. The greater the amount of local circulation the less the difference in temperature between the tubes which come nearest'to and the farthest from are used for carrying t the boiler, and it is therefore advantageous to provide a free local circulation in the bank.

Furthermore, with the long tube economizer of Figure 5, steam will have a less tendency to cause the water to belch over into the boiler than where the economizer is made up of banks of tubes, and this is, therefore, especially desirable for the high pressure element of the two-stage econo mizer, giving also great economy of floor space.

By arranging the hoppers symmetrically with respect to the banks of tubes of the economizer, the supporting members 48, that he weight of the banks, may form part of the seal. Furthermore, by causing any gases which short circuitthrough out of the hoppers to enter the open space between two of the banks,

the gases are more thoroughly mingled with the main body of the gases before they pass through the succeeding bank, and are made to contact with a larger amount of heating surfaceafter leaving the hopper than should the partition come at an intermediate point beneath one of the banks. 1

Many changes may be made in the form and arrangement of the boiler, the location of the economizer, its construction, etc., without departing from my invention.

\Vhile I have illustrated the header boxes extending longitudinally of the gas flow, it will be understood that certain features of my invention may be used with advantage irrespective of the relation between them and i the direction of the gas flow and may also be used with advantage in combinations and relations other than those 'which I have chosen for purposes of illustration.

What I claim and desire to secure by Letters Patent of the United States is 1. In a steam boiler economizer set in the waste flue of the boiler, a plurality of sets of tubes spaced along the length of the flue, each set of tubes having a series of longitudinal header boxes arranged in parallel across the flue and extending longitudinally of the flow of the gases with spaces between them to allow dropping of soot and connections between the several sets of tubes and boxes to direct the water successively through the several sets of tubes. y

2. In a steam boiler economizer'set in the waste flue of the boiler, a plurality of sets of tubes spaced along the length of the flue, each set of tubes having a series of longitudinal header boxes arranged in parallel across the ter successively through the several sets of tubes.

3. A steam boiler economizer comprising a plurality of upper and lower manifolds arranged withinthe exit flue of the boiler, the manifolds extending longitudinally of the flow of gases, and tubes connected to said manifolds in rows of non-staggered openings, some of the tubes being bent at their ends only to provide a staggered arrangement of the tubes with respect to the flow of gases and to provide a'uniform distribution of the tubes within and across said flue.-

4. A steam boiler economiz er comprising a plurality ofpaiallel manifolds located on opposite sides of. the exit flueof the boiler and tubes connectin the manifolds, the manifolds on each si e being spaced apart at least the diameter ofa tube and thetubes being ar ranged in a plurality of rows connected to each manifold and extending longitudinally of the manifold,'.with each alternate tube of a each row substantially straight and each of the remaining tubes of the row bent outwardly for the major portion of its length to position it opposite the space between said sub- 'stantially straight tube and the adjacent tube connected to the adjacent manifold.

5. A steam boiler economizer comprising a plurality of upper and lower spaced manifolds arranged within the'exit flue ofthe boiler, the manifolds extending longitudinally of the flow of gases, and tubes connected to said manifolds in rows of non-staggered openings, some of the tubes being bent attheir' ends only to provide a staggered arrangement of the tubes with respect to the flow of gases and to provide 'a uniform distribution of the tubes within and across said flue.

6. A steam boiler economizer comprising a plurality of parallel manifolds located on opposite sidesof the exit fl'ue of the boiler and tubes connecting the manifolds, the manifolds on each side being spaced apart at least the diameter'of a tube and the tubes being arranged ina plurality of rows connected to each manifold and extending longitudinally of the manifold, with each alternate tube in at least one of the rows substantiallystraight and the other tubes in such row bent outwardly for the major portion of its length to position it opposite the space between said substantially straight tube and the adjacent tube of the adjacent manifold.

7. A heat transfer device located in the exit flue of a boiler and comprising a plurality of upper and lower manifolds, the lower manifolds being spaced apart, banks of tubes spaced apart longitudinally of the flue and connecting said manifolds, soot hoppers located beneath said heat transfer device and spaced symmetrically with said banks of tubes, and seals for said hoppers for reventing the gases from short cireuiting rom one soot hopper to the next tendin 8. A heat transfer device located in the exit flue of a boiler and comprising a plurality of upper and lower manifolds extending lonitudinally of the flue, the lower manifolds eing spaced apart, banks of tubes spaced apart longitudinally of the flue and connecting'said manifolds, soot hoppers located beneath said heat transfer device and spaced symmetrically -with said banks of tubes, and seals for said hoppers arranged opposite the spaces between said banks of tubes for preventing the gases from short circuit ingfrom one soot ho per to the next.

9. A heat transfer evice located in the exit flue of a boilera'nd comprising a plurality of upper and lower manifolds extending longitudinally ofthe flue, the lower manifolds being spaced apart, banks of tubes spaced apart longitudinally of the flue and connecting said manifolds, soot hoppers located beneath said heat transfer device and spaced symmetrically with said banks of tubes, and seals for said hoppers arranged opposite the spaces between said banks of tubes for'preven'ting the gases from short circuiting from one soot hopper to the next said seals comprising supporting members for said manifolds.

10. A heat transfer device located in the exit flue of a boiler and comprising a plurality of upper and lower manifolds extending longitudinally of the flue, the lower manifolds being spaced apart and formed in sections, banks of tubes spaced apart longitudinally of the flue and connecting said sectional manifolds, soot hoppers locatedbeneath said heat transfer deviceand spaced symmetrically with said banks of tubes, and seals between the hoppers and lower manifolds comprising side being spaced apart a distance equal to at least a tube diameter, the tubes being ar-' ranged in rows extending longitudinally of the boxes, with each alternate tube of each row substantially straight and each of the remaining tubes of the row bent outwardly for the major portion of its length, to position it opposite the space between said substantially straight tube and the adjacent tube ofthe adjacent section.

12. In a heat transfer. device, a plurality of similar sections, each comprising a pair of boxes spaced apart and tubes connecting said boxes, the boxes of adjacent sections on one side being spaced apart a distance equal to at least a tube diameter, the tubes in each sectionbeing arranged in a plurality of rows exlongitudinally of the boxes, with each a ternat-e tube of each row substantially straight and each of the remaining tubes of the row bent outwardly for the major portions of its length, to position it opposite the space between said substantially straight tube and the adjacent tube of the adjacent section.

13. In a heat transfer device, a plurality of similar sections, each comprising a pair of boxes spaced apart and tubes connecting said boxes, the boxes of adjacent sections on one side being spaced apart a distance equal to at least a tube diameter, the tubes in each section being arran ed in a plurality of rows extending longitudinally of the boxes, with each alternate tube of each row substantially straight and each of the remaining tubes of the row bent outwardly for the major portion of its length, the outwardly bent parts of the latter tubes of the outerrows of two adjacent sections extending opposite the space between the boxes of said sections, with the bent tubes of one of said outer rows spaced between the bent tubes of the other outer row.

14. In a heat transfer device, a plurality of similar sections, each comprising a pair of boxes spaced apart, and tubes connecting said boxes, the" boxes of adjacent sections on one side being spaced apart a distance equal to at least a tube diameter, the tubes being arranged in rows extending longitudinally of the boxes, with each alternate tube of each row substantially straight and each of the remaining tubes of the row bent outwardly for the major portion of its length, the amount of the bend of the bent tubes and the space between the adjacent boxes being such that the tubes are substantially uniformly spaced throughout the greater portion of their lengths in planes at right angles to the axes of the boxes.

15. In a heat transfer device, a plurality of similar sections, each comprising a pair of boxes spaced apart, and tubes connecting said boxes, the boxes of adjacent sections on one side being s aced apart a distance equal to at least a tu e diameter, the tubes being arranged in rows extending longitudinally of the boxes, with each alternate tube of each row substantially straight and each of the remaining tubes of the row bent outwardly for the major portion of its length, the.

amount of the bend of the bent tubes and the space between the adjacent boxes being such that the tubes are substantially uniformly spaced throughout the greater portion of their lengths in planes at right angles to the axes of the boxes, with the tubes in each row staggered in relation to the adjacent rows.

16. In a heat transfer device, a plurality of similar sections, each comprising a pair of boxes spaced apart, and tubes connectin said boxes, the boxes of adjacent sections eing spaced apart a distance equal to at least a tube diameter, the tubes being arranged in rows longitudinally of and transversely to the axes of the boxes, with a plurality of longitudinal rows entering each box, the ends of at least some of the tubes in each longitudinal row being bent to position the straight? part of the tube opposite the space between a pair of tubes in the next adjacent transverse row of tubes.

17 In a heat transfer device, a plurality of similar sections, each comprising a pair of boxes spaced apart, and tubes connecting said boxes, the boxes of adjacent sections being spaced apart a distance equal to at least a tube diameter, the tubes being arranged in rows longitudinally of and transversely to the axes of the boxes, with a plurality of longitudinal rows entering each box, the ends of at least some of the tubes in each longitudinal row being bent to position the straight part of the tube opposite the space between a pair of tubes in the next adjacent transverse row of tubes and the transverse rows being arranged in pairs with the space along the axes of the boxes between the rows in each pair less than the diameter of a tube and the space along the axes of the boxes between the tubes of adjacent pairs of rows greater thana tube diameter.

18. In a heat transfer device, a plurality of extending circumferentially curved Wall portions provided with sets of holes each arranged in a circumferential band of said curved surface, tubes secured in said holes and connecting the two headers of each pair, at least some of said tubes being bent at their ends to enter the holes in the curved walls, the headers at each end oi, the sections having a longitudinally disposed series of openings giving access to the tubes, closures therefor, a water compartment common to a group of headers at one end of the sections, and pipes connecting the end portions of said Headers to said water compartment.

19. In a heat transfer device, a plurality of sections arranged side by side, each section having a pair of headers with longitudinally extending circumferentially curved wall portions provided with sets of holes each arranged in a circumferential band of said curved surface, tubes secured in said holes and connecting the two headers of each pair, at least some of said tubes being bent at their ends to enter the holes in the curved walls, the headers at each end of the sections having a longitudinally disposed series of openings giving access to the tubes, closures therefor, a water compartment at each end of the sections and common to the headers at each end, and pipes connecting the end portions of the headers to said water compartment.

20. In a heat transfer device, a plurality of sections arranged side by side, each section having a pair of headers with longitudinally extending circumferentially curved wall portions provided with sets of holes each arranged in acircuiufercntlal band of said curved surface, tubes secured in said holes and' connecting the two headers of each pair, at

least some of said tubes being bent at their connecting each of said compartments to the end portions of some of said headers.

21. In a heat transfer device, a plurality of sections arranged side by side, each section having a pair of headers provided with walls having sets of tube holes, tubes secured in said holes and connecting the two headers of each pair, at least some of said tubes being bent at their ends to enter the holes in the header walls, the headers at each end of the sections having a longitudinally dispos- 'ed series of openings giving access to the tubes, closures therefor, a water compartment common to a group of headers at one end of the sections, pipes connecting the end portions of said headers to said water compartment, means causing hot gases to flow across said tubes, and the spacing of said tubes being substantially uniform across the gas stream.

22. In a heat transfer device, a plurality of sections; arranged side by side, each section having a pair of headers provided with walls having sets of'tube holes, tubes secured in said holes and connecting the two headers of each pair, at least some of said tubes being bent at their ends to enter the holes in the header walls, the headers at each end of the sections having a longitudinally disposed series of openings giving access to the tubes, closures therefor, a water compartment common to a group of headers at one end of the sections, pipes connecting the end portions of said headers to said water compartment, means causing hot gases to flow across said tubes, the spacing of said tubes being substantially uniform across the gas stream, and the tubes being staggered in the direction of flow of said stream.

23. In a heat transfer device, a plurality of sections arranged side by side, each section having a pair of headers with longitudinally extending circumfercntially curved wall portions provided with sets of holes each arranged in a circumferential band of said curved surface, tubes secured-in said holes and connecting the two headers of each pair, at least some of said tubes being.bent at their ends to enter the holes in the curved walls, the headers at each end of the sections having a longitudinally disposed series of openings giving access to the tubes, closures therefor, a water compartment common to a group of headers at one end of the sections, and pipes connecting the end portions of said headers to said water compartment, the adjacent headers in a group being spaced apart a clear distance greaterthan a tube diameter.

24. In a heat transfer device, a plurality of sect-ions arranged side by side, each section having a pair of headers provided with walls having sets of tube holes, tubes secured in said holes and connecting the two headers of each pair, at least some of said tubes being bent at their ends to enter the holes in the header walls, the headers at each end of the sections having a longitudinally disposed series of openings giving access to the tubes, closures therefor, a water compartment common to a group of headers at one end of the sections, pipes connecting the end portions of said headers to said water compartment, means causing hot gases to flow across said tubes, the spacing of said tubes being substantially uniform across the'gas stream, and in the direction of flow of said stream.

25. In a heat transfer device, a plurality of sections arranged side by side, each section having a pair of headers provided with walls having sets of tube holes, tubes secured in said holes and connecting the two headers of each pair, at least some of said tubes'being bent at their ends to enterthe holes in the header walls, the headers at each end of the sections having a longitudinally disposed series of openings giving access to the tubes,

closures therefor, a water compartment common toa group of headers at one end of the sections, pipes connecting the end portions of said headers to said water compartment, means causing hot gases to flow across said tubes, and the spacing of tubes being substantially uniform longitudinally of said headers and transversely thereof.

26. In a heat transfer device, a plurality of sections arranged side by side, each section having a pair of headers provided with walls having sets of tube holes,.tubes secured in said holes and connecting the two headers of each pair, at least some of said tubes being bent at their ends to enter the holes in the header walls, theheaders at each end of the sections having a longitudinally disposed series ofopenings giving access to the tubes, closures therefor, a water compartment common to a group of headers at one end of the sections, pipes connecting the end portions of said headers to said water compartment, means causing hot gases to flow across said tubes, the spacing ofsald tubes being substantially uniform across the gas stream, and the headers being spaced apart a clear distance greater than a tube diameter.

27. In a heat transfer device, a plurality of curved surface, tubes secured in said holes and connecting thetwo headers of each pair, at least some of said tubes being bent at their ends to enter the holes in the curved walls, the headers at each end of the sections having a longitudinally disposed series of openings giving access to the tubes, closures therefor, a water compartment common to a group ofheaders at one end of the sections pipes connecling the end portions of said headers to said water compartment, the adjacent headers in a group being spaced apart a clear distance greater than a tube diameter, and the tubes being spaced substantially uniform lengthwise of said headers.

28. In a heat transfer device, a plurality of. sections arranged side by side, each section having a pair of headers provided with walls having sets of tube holes, tubes secured in said holes and connecting the two headers of each pair, at least some of said tubes being bent at their ends to enter the holes in the header walls, the headers at each end of the sections having a longitudinally disposed series of openings giving access to the tubes, closures therefor, a water compartment common to a group of headers at one end of the sections, pipes connecting the end portions of said headers to said water compartment,

means causing hot gases to flow across said tubes, and the spacing of said tubes being substantially uniform across the gas stream, said headers being spaced apart a clear distance greater than a tube diameter, the major por tions of the tube lengths being spaced apart less than a tube diameter.

29. In a heat transfer device, a plurality of sections arranged side by side, each sec tion having a pair of headers with longitudinally extending cireumferentially curved wall portions provided with sets of holes each arranged in a circumferential band of said curved surface, tubes secured in said holes and connecting the two headers of each pair, at least some of said tubes being bent at their ends to enter the holes in the curved- Walls, the headers at each end of the sections each having a longitudinally disposed series of openings giving access tothe tubes, closures therefor, a water compartment common to a group of headers at one end of the sections, and pipes connecting the end portions of said'he aders to said Water compartment, thenest of tubes connecting a pair of headers being wider-than the distance between center lines of adjacent headers.

30. A heat transfer 'devicecomprising groups'ofheaders disposed on opposite sides of a gas pass, the headers of both groups having longitudinally extending circumferentially curved Wall portions provided with sets of holes, eaeh' arranged in acircumferential band of said curved surface, a substantially continuous bank of tubes extending across said pass and having the tubes therein 

